- Cyclic strain influences the expression of the vascular endothelial growth factor (VEGF) and the hypoxia inducible factor 1 alpha (HIF-1alpha) in tendon fibroblasts. Petersen, W., Varoga, D., Zantop, T., Hassenpflug, J., Mentlein, R., Pufe, T. J. Orthop. Res. (2004)